Next up: Next up, a new Tamron 17-50/2.8 XR DiII LD IF and whatever other murky BS marketing suffixes can be had- but does not have the stabilization that the newest version has. Good price and pretty good performance except that it has what appears to be the worst back focusing problems of any of my AF lenses (on my D7000). So I manually focus it when I need critical sharpness.

And lastly, a (new to me) used Sigma 150-500/5-6.3 APO with optical stabilizing. Seems to be well made, and with decent optics... but it is no Nikkor in the same tele range. But then again, those are 6x as much cost. Contrast is good, bokeh seems very nice (see first image). Some early handheld w/OS on.

1. Bokeh seems nice on this lens.

2. Dealing with the back focus issue common on D7000's. Otherwise, seems like a good rendering.

3. I know- poor exposure made poorer in PP. Still learning, but decent sharpness handheld at 500mm with OS on.

Tyler - I know two of the lenses fairly well. We own both the Samyang (Rokinon and many other names) f/3.5 8mm fisheye (the older version with the fixed lens hood) and the Sigma f/5.6 -6.3 150-500mm.

I don't use the fisheye a lot. It is very much a special purpose lens and the only reason I bought it was that it is so inexpensive. Optically and mechanically quite good, but I have to shoot it 100% manually on my D90. As you have noted, virtually everything is in focus. There is a tendency to have a bit of vignetting from the lens hood showing at the edges of the frame.

The Sigma has not been great. It had to go back to Sigma twice in the first 6 months that we owned it. The first time the autofocus motor and electronics went, and the second time the electronics went again a couple of months later. It focuses reasonably quickly and optically it is okay, about the same as the f/4.5-5.6 80-400mm Nikkor. Mechanically, it is not a particularly robust lens. It takes 86mm filters which are pricey and not always easy to find.